A&M cotton research could open new front in war on weeds

COLLEGE STATION — Scientists at Texas A&M University are hopeful they’ve developed the Kryptonite for what’s been a losing battle against herbicide-resistant weeds now choking cotton fields across the southern U.S.

If it works as well in the San Angelo test field as it has in a campus greenhouse, the technology could prove revolutionary to a crop that in some regions has become vulnerable to weeds that have developed resistance to three generations of pesticides.

Through a painstaking process, the A&M scientists successfully introduced a genetic trait that allows cotton to thrive in soil that has been enriched with phosphite, which has one less oxygen atom than the phosphate used in traditional fertilizers. Because the weeds don’t have the same trait, they are essentially starved of nutrients.

For decades, the magic formula was to spray fields full of cotton genetically engineered to resist herbicides, such as Roundup, and then watch the weeds dutifully die. But nature started mutating the weeds so they, too, resisted the chemicals.

The result has farmers spending some $9 billion a year in a desperate search for the right mix of older and newer weed killers. In the Mississippi Delta, 60 to 70 percent of the weed populations have developed three-way resistance. Farmers are struggling to keep up.

“If this technology had come along 20 years ago people would say, ‘Why bother? You’ve got Roundup,’” said Kater Hake, vice president of agricultural & environmental research for the industry group Cotton Inc. “Yeah, well, Roundup doesn’t work now.”

Hake referred to the new technology as the “Superman” of weed control, a mighty successor to Monsanto’s glyphosate-based Roundup and others.

“We have not had a new herbicide mode of action since the early ’80s,” Hake said. “We got a new mode of action approximately every year for about 30 years and since then it’s just been flatlined.”

In Texas, the nation’s leading cotton-producing state, the commodity contributes an estimated $24 billion a year to the economy. In addition, Hake said, cotton is seeing a resurgence in demand as both a natural fiber and one that’s better for the environment than petroleum-based polyester.

The ptxD gene that allows absorption of phosphite was first isolated by William Metcalf of the University of Illinois. A Mexican research team then patented the concept of introducing the gene into plants to make them more competitive against weeds in the field.

An A&M team led by Keerti Rathore has been taking the technology to cotton plants. Unlike easily modified “plant mice” such as tobacco or arabdioxis, cotton is a slow-growing, complex plant and notoriously hard to genetically transform.

During a recent tour of the temperature-controlled lab, Rathore showed petri dishes full of cells that take an average about 10 months to produce a plantlet. From the plantlet, it can take another year to grow a plant with a root system strong enough to survive in the greenhouse and produce seeds.

Each month, research associate LeeAnne Campbell transfers cell cultures known as calluses to new nutrient-rich mediums, visually editing out contaminants or undesirable growths.

“It’s kind of like a treasure hunt,” she said. “You’re always looking for the right colors and the right textures.”

Validation came in the greenhouse.

Weed scientist Muthu Bagavathiannian had no trouble finding herbicide-resistant pigweed, which can produce up to a million seeds per plant compared to cotton’s 200 to 300.

Cotton lacking the gene pioneered at A&M got crowded out by the weeds in fields where the soil was fertilized with phosphate.

But transgenic cotton grown on phosphite-fertilized soil grew nicely while the weeds did not.

“It is a very simple yet elegant technology that has the potential to revolutionize agriculture as we know it,” Rathore said.

The greenhouse plants are now producing the seeds for the next step, which will be on a carefully controlled field in San Angelo.

The field was chosen because it is naturally low in phosphorous, as a high-phosphorous field would feed the weeds and defeat the purpose.

That won’t be a problem in most parts of the world because phosphorous is in dangerously short supply. Current stores of the vital element are closely guarded in a few places, including Morocco, China and Florida. European scientists have been looking for ways to reclaim phosphorous from animal and human waste.

For most U.S. farmers, the problem has been overuse.

“Our farmers put too much fertilizer on their fields, nitrogen and phosphorous in general,” Rathore said. “I think for us to kind of really utilize this technology we’ll have to kind of wean the farmers off, using less and less.”

His hopes for the technology are threefold: farmers will be able to spend less on inputs including fertilizers, herbicides and water otherwise getting “stolen” by the weeds; phosphorous in the form of phosphate will be depleted at a slower rate; less of the nutrient will wash off into waterways, where it contributes to algae blooms plaguing the world’s oceans and great lakes. He’s also confident the technology will work in other crops.

Phosphite fertilizers will need to become more readily available, but Rathore said there are companies ready to step up to sell it. Phosphite is already used in potato production, as it inhibits the fungi that caused late blight and, in the 19th century, Ireland’s Great Famine.

This is not Rathore’s first foray into the genetically modified cotton world. About a decade ago, his team made headlines for removing a toxin from cottonseed and making the seed a valid, high-protein animal feed. Countries including India and Mexico, which are typically resistant to genetically modified crops, have been receptive to the technology.

“That will be maybe the fifth product developed by a public institution that has gone to that level,” Rathore said. “Most of these GMO products are developed by companies like Monsanto, Bayer, Syngenta and so on.”

The long-term challenge will be making sure growers use a mixed-bag approach to reduce the likelihood that weeds will eventually mutate their way toward being able to feast on phosphite.

Nature has outsmarted GMO technology by mutating the very site that the herbicide targets or by copying the target sites so many times that the herbicide can’t adequately attack.

“If you just imagine like a lock and key, you’ve got to have the right combination to be able to open it,” said Bagavathiannian, the weed scientist. “ … Nature changed the locks.”

The new technology involves not so much an attack approach as a genetic change to the plant’s metabolism, and the researchers said it would be unlikely weeds would generate a similar change on its own.

“In order for them to be able to do that, one of the genes will have to have several stretches of mutations in that gene,” Rathore said. “That is unlikely to happen.”

But it’s not outside the realm of possibility, and farmers will have to be careful to use it as part of a multifaceted resistance management program.

Jimmy Roppolo, general manager of the United Agricultural Cooperative cotton in Danevang, about 80 miles south of Houston, said weeds are the biggest problem facing producers.

“You know everybody thought the answer to the world’s problems was Roundup-ready cotton, you could spray it with Roundup, a very safe herbicide, and actually destroy everything but the cotton,” he said. “But the weeds found their way.”

In drought years like this that make for a poor grain crop, farmers are more dependent on their cotton, he said. At this point, they’re very receptive to the promises of the new technology.

“The producers are willing to look into anything that will help them save on production,” he said. “They’d love to put out less herbicides, less fertilizer and produce their crop at a lower cost.”

Bugging bugs to understand Chagas disease

Scientists in the United States are attaching miniature radio transmitters to the backs of blood-sucking insects known as kissing bugs, in an effort to learn more about the disease-carrying creatures.

Researchers in Texas glued transmitters weighing 200 milligrams to different species of kissing bugs, also known as triatomine bugs, so they could track their movements. The insects, from the family Reduviidae, typically move at night and hide during day, and uncovering their movements could help reduce their impact as disease carriers.

In a report published in the Journal of Medical Entomology, lead author Gabriel Hamer, from Texas A&M University, says: “While studying kissing bugs in Texas, we have been perplexed regarding their movement behaviour.”

Hamer says during their research, he and his colleagues observed dozens of kissing bugs emerging simultaneously from natural habitat and arriving at people’s homes.

“Where are they coming from?” he says. “How far are they travelling? Why are they dispersing? These observations and others provided the motivation to try to utilise a methodology to track wild kissing bugs and study movement.”

A 2015 report by broadcaster CNN into the insects says the nocturnal, 2.5-centimetre-long bugs are nicknamed kissing bugs because they feeds on mammals’ blood, and particularly like to bite near the lips and eyes of animals, including humans, while they sleep.

The bites can turn deadly when bugs infected with the parasite Trypanosoma cruzi defecate and the faecal matter infects the bite. The infection is known as Chagas disease.

Hamer and colleagues worked with three families who had routinely found kissing bugs around their homes. The researchers tagged and tracked 11 of the insects, and painted the transmitters with fluorescent paint to aid in rediscovery.

Over 12 days, the researchers found the insects walked on average about three metres, up to a maximum of about 20.

One particular kissing bug revealed just how elusive they can be. It was initially captured near a dog kennel and was found the next day in a small slit where the top and bottom of the plastic kennel fitted together.

“This would have been a very difficult location to find without the use of radio telemetry,” Hamer says.

“The owner, who has lost several dogs to canine Chagas disease, regularly removes kissing bugs from inside and under the kennels, but any kissing bugs in the cryptic hiding location in the joint of the doghouse would have been missed.”

According to the US Centres for Disease Control and Prevention (CDC), Chagas disease – first described in 1909 by Brazilian doctor Carlos Chagas – is transmitted to animals and people by insects that are found only in the Americas, mainly in rural areas of Latin America where poverty is widespread.

The CDC estimates about eight million people in Mexico, Central and South America have the disease, most of whom do not know they are infected. If untreated, infection is lifelong and can be life-threatening.

The CNN report says there are about 300,000 cases of Chagas in the US but most of those were contracted in other countries. Nevertheless, species have been detected in 28 states, with more than 50% carrying Trypanosoma cruzi.

The new study marks an initial foray into tracking triatomines via radio telemetry, but it could open the door for more in-depth studies into kissing bugs’ movements. Hamer says he is eager to continue this research and hopes other entomologists and vector-management researchers will take advantage of advances in radio telemetry to track insect behaviour.

“Kissing bug dispersal and movement behaviour is fundamentally involved in the exposure of dogs and humans to the agent of Chagas disease,” he says. “We hope our research can continue to make advancements in our understanding of this kind of basic biology of the insect vector that will improve our ability to intervene and minimise Chagas disease.”Back to top

Verify: What’s the best way to fight off mosquitoes?

When it comes to fighting mosquitos a lot of people are weirded out by chemical repellents, like DEET. That what drives a growing market for natural repellents. But are chemicals really bad and how well do naturals work?

BIG-CITY MOSQUITO CONTROL

Let’s start with chemicals. Communities across America fight mosquitoes in the most efficient way possible, by spraying large areas with insecticide.

The most common chemicals are called pyrethroids. It’s a man-made insecticide based on the chemicals naturally found in chrysanthemum flowers.

The EPA says they poses no a risk to people. But pyrethroids are sprayed at night because they can be harmful to birds and insects that fly during the day.

Now, the city of Garland, Texas, is trying something even less toxic.

“What is this?” I ask Jeff Crocker, with the Garland.

“This is VectoBac WGD,” he says.

It’s a spray that Garland will begin using shortly to manage mosquito populations.

VectoBac is known as a BTi which kills mosquitoes in their larvae stage before they even hatch. The EPA says BTi poses no risk to people and no risk the environment because it is a naturally occurring bacteria that specifically poisonous to mosquitos.

It’s applied using a powerful sprayer that mists the compound up into the air so it can settle down into backyards.

“The way I think about mosquitos is I want to kill the ones at my house. How about you?” I ask Crocker.

“Mosquitos aren’t really bound by fences or yards or city limits. Mosquitos are going fly within their range,” Crocker says.

That’s about a half-mile and that’s why it can take an industrial strength to control mosquitos across an entire community.

“The control is because I’ve done this hundreds of times. It’s consistency we’re looking for. I’m just trying to compare my now results with 3 years ago results,” says.

“These are real world mosquitos. You can replicate it all in a lab, but that doesn’t’ help you in the real world,” Steve adds.

BUG EXPERT

My last visit is with Dr. Mike Merchant, an insect expert with Texas A&M. And I want to know how effective are repellents made from plants?

“Do we know if they work?” I ask.

“Not necessarily. A lot have insecticidal properties. They are plant-based oils. Which are in plants, in the first place, to protect the plants from insects,” he says.

“But how good are they? Are they good enough to protect your family from mosquito-borne diseases? That’s not addressed by the current system,” Merchant adds.

The current system works like this…

There’s a long list of EPA approved insecticides, reviewed for human safety and effectiveness. So DEET, for example, is on the list.

“What about DEET? Is DEET safe?” I ask.

“It has been used on millions probably billions of people around the world and used safely. Not to say there are some people who have made claims that DEET has some risks associated with it. But the risks, over and over, are shown to be very minimal,” Merchant says.

And that’s even true for kids. The American Academy of Pediatrics recommends 10% to 30% DEET for kids over two months.

But there’s one more thing. The EPA has this list of 45 natural ingredients that are exempt from regulation. That’s what natural repellents are made from but they are not tested for effectiveness against mosquitoes.

“When you’re out in the backyard with your kids you don’t want to say, ‘maybe this will protect my child. You want something that has some scientific clout behind it,” Merchant says.

CONCLUSION

So, when it comes to the fight against mosquitos what’s better: natural — like that list of 45 natural ingredients — or chemical?

Well, we’ve learned that both are safe. But if you want to know — for sure — that your repellant is effective the answer is chemical.

The EPA has a website where you can find the repellent that’s right for you. Many people who want a natural repellent — proven to work — choose lemon oil of eucalyptus because it is an EPA-approved insecticide.

Got something you want verified, send me an email: david@verifytv.com

Editor’s Note: The video portion of this story has been revised to reflect that there are a small number of plant-based products, for example lemon oil of eucalyptus, that are regulated by the EPA and considered both safe and effective. The original video did not contain that language.

How farmers could be hurt by a trade war with China

Bloomberg’s Alan Bjerga and Luis Ribera, an associate professor at Texas A&M, discuss how farmers could be impacted by U.S. tariffs on Chinese goods. They speak on July 3 on “Bloomberg Daybreak: Americas.” (Source: Bloomberg)Back to top